Power boosted keyboard assembly



1963 E. s. SHAFFSTALL ETAL 3,114,501

POWER BOOSTED KEYBOARD ASSEMBLY 4 Sheets-Sheet 1 Filed April 3, 1961 INVENTORS. Evsaerr G- SHAFFSTALL BY and Esrou H. SMITH flawml, 11 0M m'! 4 MW 1 Afforngvs Dem 1963 E. G. SHAFFSTALL ETAL ,1 0

POWER BOOSTED KEYBOARD ASSEMBLY 4 Shegts-Sheet 2 Filed April 5, 1961 rlllllllilluL INVENTORS. EVERETT G. SHAFFSTALL BY and ESTON H.$Mm4 Xmwm! 20m $01M $10M 14f70meys Dec. 17, 1963 E. G. SHAFFSTALL ETAL 3,114,501

POWER BOOSTED KEYBOARD ASSEMBLY Filed April 5, 1961 4 Sheets-Sheet 3 5 "I S no l l l E g I a 8 9- .5 5 I' I o a W V 8 '2 g 1 0 E0 h 3 :g 2 a 3| rw i g 6; 0 o E d g g EVERETT G. SHAFFSTALL BY and Esrou H. SMITH WMMfl/W Mfume vs INVENTORS.

United States Patent Ofi ice 3,114,501 POWER BOOSTED KEYBOARD ASSEMBLY Everett G. Shalfstall and Eaton H. Smith, Indianapolis,

Ind., assignors to Shalfstall Equipment, Inc., Indianapolis, Ind., a corporation of Indiana Filed Apr. 3, 1961, Ser. No. 100,204 7 Claims. (Cl. 234-123) This invention relates generally to power boosted keyboard assemblies and in particular to a power boosted keyboard attachment for conventional tape perforating apparatus used to prepare coded perforations in tape to be used in the operation of slug linecasting machines.

To speed up and render more convenient the setting of type by slug linecasting machines, it has become conventional to provide such machines with attachment devices which automatically operate the linecasting machine. The matrix or mat releasing mechanism of a machine provided with such an attachment device is operated in response to a perforated tape fed into the attachment rather than by direct manual operation of the linecasting machine keyboard by an operator. These attachments permit operation of the linecasting machine at high speeds and permit the controlling tape to be perforated in advance of operation of the line casting machine by a tape perforating machine operator at a location remote from the linecasting machine.

The present invention is directed to a power boosted keyboard attachment which is described as incorporated into, and replacing the keyboard of, a tape perforator device as manufactured by The Teletype Corporation. The operation of the Teletype tape perforator is not described in detail herein since this device is well known in the art and is but environment for the present invention. The Teletype Corporations tape perforator is disclosed in US. Patents 2,059,250, 2,080,424 and 2,083,570. The present invention is described as incorporated into a tape perforator of the type disclosed in the above mentioned patents but it will be understood that it could be utilized with other keyboard operated devices.

In the conventional operation of the apparatus referred to above a tape is perforated on the perforator by an operator using the keyboard of the perforator to transcribe the material to be printed. Because several mechanical operations must be performed by the keys, they offer considerable resistance to the fingers of the operator as the keys are struck. This resistance is of a far higher magnitude than that encountered in a conventional typewriter or in the keyboard of a conventional slug linecasting machines. An average operator, operating a conventional perforating device at, for example, a speed of five hundred and fifty lines per hour, will exert a total force of some twenty thousand pounds over a working day. On conventional perforating devices the key stroke is relatively long and there is little cushioning overtravel.

The primary object of the present invention is to provide a power boosted keyboard assembly for use on conventional tape perforating devices which will permit tape to be perforated with relatively light and relatively short finger stroke of the keyboard.

A further object of the present invention is to provide a power boosted keyboard assembly in which each 3,114,501 Patented Dec. 17, 1963 0f the keys may be uniformly spaced from each other both vertically and horizontally.

A further object of the present invention is to provide an assembly of the type referred to in which the operating stroke of the keys is relatively short and in which some forty percent of the relatively short stroke is cushioning overtravel.

A further object of the present invention is to provide an assembly of the type referred to in which each key lever and its accompanying power boosted operating elements are mounted in a modular, unitary sub-assembly permitting their individual removal from the total assembly for repair or replacement.

The full nature of the invention will be understood from the accompanying drawings and the following description and the claims.

FIG. 1 is a perspective view of the apparatus of the present invention enclosed in an outer cover and incorporated into a conventional tape perforator device.

FIG. 2 is a perspective view of the frame supporting the key sub-assemblies of the present invention and having portions of the spaceband actuator broken away to prevent obscuring of the remaining portions of the structure.

- FIG. 3 is a side sectional view illustrating one bearing mounting of a power driven shaft disposed within the frame of FIG. 2.

FIG. 4 is a perspective view of one of the keyboard sub-assemblies mounted in place within the frame shown in FIG. 2.

:FIG. 5 is a side sectional view taken generally along the line 55 of P16. 4.

FIG. 6 is a side sectional view taken generally along the line 6-6 of FIG. 4.

FIG. 7 is an exploded view illustrating the linkage between the power driven shaft and the drive motor for the shaft.

FIG. 8 is a detailed view of the spring component of the linkage of FIG. 7.

FIG. 9 is a fragmentary view of one of the mounting plates, each of which carries one of the keyboard actuating assemblies, the variously sized key levers being illustrated in FIG. 9 in broken lines to indicate their orientation with respect to their respective mounting plates.

FIG. 10 is a transverse section view of the spaceband actuating bar and the spaceband key actuated by the bar.

FIG. =11 is a side view of one of the key trip assemblies carried by its respective mounting plate and shown in quiescent condition.

FIG. 12 is a view similar to FIG. 11 but showing component parts in the position assumed just after tripping but before the key lever has reached the downward limit of its stroke.

FIG. 13 is a view similar to FIG. 12 but showing the drive shaft advanced to a point where the right hand end of the actuating lever is in its maximum downward position.

FIG. 14 is a side view illustrating the structure of the actuating lever.

FIG. 15 is a top plan view of the actuating lever shown in FIG. 14.

FIG. 16 is a fragmentary end view of the structure of the present invention illustrating one form of a locking mechanism for the actuating levers.

FIG. 17 is a view of the locking mechanism of FIG. 16 but taken from the opposite end of the keyboard assembly.

Referring initially to FIG. 1 there is shown a tape perforator of conventional type having a counting scale 11 and a mounting board 12 for the printed material to be transferred to the perforated tape. It will be understood that a complete conventional tape perforator device includes a keyboard at its front panel and that the perforator operator strikes the keys so as to perforate a blank tape with a code which identifies the letters struck on the keyboard. To accommodate the apparatus of the present invention, the conventional tape perforator shown in FIG. 1 has been modified by removal of its keyboard, such removal being accomplished by cutting its key levers so that they protrude only a short distance outwardly from the front panel of the perforator device. The apparatus of the present invention is then attached to the perforator device by any suitable means, such apparatus being shown at 13 in FIG. 1. In FIG. 1 a housing 14 encloses the component parts of the present invention, the housing having an open tilted face which exposes an array of keys 16 and a spaceband bar 17.

The general organization of the frame enclosed by the housing 14 and the power drive will now be described with reference to FIGS. 2-8. The frame includes a left side plate 18 and a right side plate 19. Extending transversely between the side plates and supported by means of screws 21 are a front bar 22, a stepped rear bar 23 and mounting blocks 24. Extending between the mounting blocks 24 and removably secured thereto by means of screws 26 is a top bar 27. Each of the bars 22, 23 and 27 is provided with a series of horizontally aligned slots or grooves 22a, 23a and 27a, the slots 27a extending only partially through the bar 27. The slots serve to removably support the mounting plate portion of a modular key trip sub-assembly as will subsequently be more fully described with reference to FIG. 4.

The side plates 18 and 19 each carry threaded fulcrum screws 28 locked in position by nuts 29, the inner ends of the screws 28 being received in suitable axial apertures in a shaft 31 serving to clamp to the ends of shaft 31 and serving to support the shaft in stationary relation with the plates 18 and 19 While permitting the outwardly extending members 32 to rock upon the shaft 31. The members 32 extend adjacent the inner faces of the plates 18 and 19 and support the spaceband bar 17. The spaceband bar 17 and its cooperation with the spaceband key will be subsequently described with reference to FIG. 10.

Referring now principally to FIGS. 2, 3, 7 and 8, the drive or actuating shaft and its mounting will be described in detail. In FIG. 2, it will be noted that the exterior face of the plate 18 carries a removable bearing housing 33 having sidewardly extending tabs 34 accommodating the mounting screws 36. As may be clearly seen in FIG. 3, the bearing assembly includes the cup shaped housing 33 accommodating a ball bearing structure 37, the outer race 38 of which seats in an annular undercut 39 in the plate 18. The inner race of the bearing assembly 37 accommodates the end 41 of a shaft 42 which spans the plates 18 and 19. The shaft 42 is provided with an exterior surface 43 of resilient material such as rubber. It will be noted that the aperture 44 in the plate 18 is sized so as to permit withdrawal of the shaft 42 therethrough when the bearing housing is removed from the plate 18. The opposite end of the shaft is formed similar to that shown in FIG. 3 and is journaled in a bearing assembly 46 (FIG. 2) carried on the inner face of the side plate 19. The extending end 47 (FIG. 7) of the shaft 42 can be withdrawn from the inner race of the bearing assembly 46 as the shaft 42 is withdrawn through the aperture 44 in the plate 18.

Referring now specifically to FIGS. 7 and 8 the coupling of the shaft 42 to its drive motor will now be described.

As will be evident from FIG. 7, the right hand end 47 of the shaft 42 has an axial counterbore 48 provided therein, the bore being spanned by a transverse pin 49. The bore 48 receives the body portion of a coiled spring 51, the hooked end 52 of the spring encircling the pin 49. The opposite end 53 of the spring is formed to provide an elongated planar configuration which is received in a central slot 54 in a hub member 56. The member 56 is enclosed by a sleeve 57 and is locked upon the drive motor shaft 58 by any suitable means such as the setscrew 59. The motor shaft 58 is driven by a conventional electric motor 61 mounted adjacent the outer face of the side plate 19 with its shaft 58 generally coaxial with the shaft 42. It will be noted that the coupling just described permits a somewhat resilient transfer of torque from the motor shaft 58 to the shaft 42 and that the arrangement permits convenient separation of the shaft end 47 from the member 56 as the shaft 42 is withdrawn from the assembly as previously described.

Referring specifically to FIGS. 4, 5 and 6, the arrangement for inserting and withdrawing the modular key trip sub-assemblies from the frame will now be described. Each of the key trip sub-assemblies is mounted on one face of a support plate such as that indicated at 62. Each of the plates of which plate 62 is typical are provided with a sidewardly extending top flange 63, front flange 64 and base flange 66. The flanges terminate somewhat short of the side margins of the plate 62 so as to provide an unflanged portion 67, 68 and 69 (FIG. 5). The unflanged portion 67 is received within the appropriate one of the slots 27a in the top bar 27 and the portion 68 of the plate 62 is received within the appropriate one of the slots 22a in the front bar 22. As may best be seen in FIG. 6, the flange portions 64 and 66 of the plate 62 serve to locate the unflanged portion 68 within the appropriate slot 22a, the base flange 66 of the plate 62 resting upon a resilient damping element 71 which is bonded to and extends along the upper face of the front bar 22. The rear lower corner of the plate 62 is supported in the appropriate one of the slots 23a in the rear bar 23, the unflanged portion 69 of the plate 62 extending into the slot. Extending through the portions of the bar 23 defining the slots 23a is a positioning rod 72 and the adjacent portion 69 of the plate 62 is provided with a half-round indentation 73 to accommodate the rod 72 whereby the plate 62 is rotated vertically within the rear bar 23.

It will be noted that the mounting arrangement for the key trip mechanism supporting plates 62 is such that any one of the plates 62, and the mechanism carried thereby, may be removed individually from the assembly merely by removing the top bar 27 and withdrawing the shaft 42 endwise from the assembly. The bar 27 may be removed by removal of the screws 26 and the shaft 42 may be withdrawn by separating the bearing housing 33 from the plate 18. With the shaft 42 and bar 27 removed, each of the plates 62 may be extracted from the front bar slots 22a and the rear bar slots 23a. The key trip mechanism carried by each of the plates 62 may thus be made readily accessible for repair or replacement. When the particular plate 62 supporting the spaceband key trip mechanism is to be removed, the procedure described above is followed with the addition that the screws 28 are withdrawn from the plates 18 and 19 permitting the members 32 and the spaceband bar 17 to be withdrawn from the assembly.

Referring now to FIGS. 9-15, the modular key trip assemblies will be described in detail. As may be seen in FIG. 9, the inclined portion of each of the plates 62 has extending therefrom one of the key levers 76, the key levers being shown in broken lines in FIG. 9 to illustrate their alternate placement on the various plates 62. Each plate 62 carries a single key lever guide 77, the positioning of the guide on the plate varying with the length of the particular key lever 76 with which it cooperates. The guides 77 are shown in broken lines in FIG. 9 to illustrate their alternate positioning on the plate 62. The longest of the key levers is the spaceband key lever 78 which is formed to provide a sidewardly extending flange 79 at its upwardly extending end. As may be seen in FIG. this flange 79 on the spaceband key lever is engaged by the spaceband bar 17, the adjacent end of the spaceband key being depressed when the bar 17 is depressed. The upwardly extending ends of the keys 76 are formed as indicated at 76a to accommodate conventional finger engagement elements. In the subsequent description of the key trip mechanism a single one of the plates 62 with its appropriate trip mechanism is described, however, it will be understood that each of the plates carries a similar trip mechanism, the only variation being the length of the key levers.

Referring now to FIG. 11, it will be noted that each of the plates 62 has cut away portions 81, 82, 83 and 84 therein. The shaft 42 extends through the cut out area 83 in the plate and is continuously rotated counter-clockwise as viewed in FIG. 11. Extending horizontally across the plate 62 somewhat above the shaft 42 is an actuating lever 86. As may best be seen in FIGS. 14 and 15, the actuating lever 86 is formed of two identical plates 87 and 88 which are spaced apart by an element 89 interposed therebetween. As indicated at 91 in FIGS. 14 and the plates 87 and 88 are outwardly offset and their adjacent ends embrace an extension member 92. The plates 87 and 88 and the members 89 and 92 are secured together by any suitable means such as rivets. The plates and the member 89 are slotted as indicated at 93 to receive the shank of a headed rivet 94, the shank of the rivet acting as a fulcrum point for the lever 86 and the slot 93 permitting the lever to move upwardly with relation to the fulcrum point under certain overload conditions. The right hand end of the lever 86 is formed outwardly on both sides of the member 89 as indicated at 96. The member 89 is cut away at this corner area and the pocket thus formed accommodates the extending end 97 of the tape perforator key lever, the extending end 97 of the perforator key lever being that portion remaining after the perforator key levers are cut away as previously described in preparing the perforator for incorporation of the apparatus of the present invention. As indicated at 98 the member 89 is formed so as to present a convex surface to the upper edge of the perforator key portion 97 as the lever 86 is rocked in clockwise direction about the fulcrum point 94.

' As will be evident from FIG. 11 the outwardly offset portion 91 of the lever 86 supports a cam 99, the cam being received within the lever and freely pivotable about the rivet 101. The cam 99 is formed by two spaced plates having identical outer configuration with the distance between the plates being spanned by a pin 102. As may be seen in FIG. 11 the cam is normally positioned as there shown with the pin .102 engaged by the stop finger 103 which is carried by the plate 62 and extends downwardly into the cut away area 83. A tension spring 104 extends between the lever 86 and a tab 106 integral with the plate 62, the tension spring serving to bias the lever 86 in a counter-clockwise direction about its fulcrum 94. An overload spring blade 107 is hooked at one of its ends about the headed rivet 108 and at its opposite end engages the sidewardly extending tab 109 which is integral with the plate 62. The curved upper portion 111 of the spring blade engages the flange 63 formed on the plate 62. When the spring blade 107 is installed it is resiliently deformed so that the apex portion 112 is spaced slightly from the upper edge of the lever 86. When the lever is moved upwardly with relation to the fulcrum rivet 94, it will be understood that the spring blade is engaged by the lever and resists such upward movement. The apex 112 of spring 107 must be spaced vertically somewhat from the lever 86 and must be located horizontally so that it is substantially vertically aligned with the fulcrum 94 to provide proper operation of the overload spring. The configuration and mounting 6 of spring 107 is such that the proper positioning of its apex 112 can be conveniently accomplished. By bending tab 109 upwardly or downwardly, as viewed in FIG. 11, the apex 112 can be displaced vertically, and by altering the curvature of portion 111 of the spring by bending the apex 112 may be adjustably positioned horizontally.

Adjacent the left hand end of the lever 86, the plate 62 supports a lever guide composed of two identical plates 113 separated by a spacer 114 interposed therebetween. Rivets 116 serve to mount the guide on the plate 62. The space between the plates accommodates the extending end 92 of the lever 86 and also the extending end of a key release lever 117. As may be seen in FIG. 11 the end 92 of the lever 86 rests against the upper end 118 of the key release lever 117. The key release lever is pivoted on the post 119, the inner face of the lever being spaced from the adjacent face of the plate 62 by means of a spacer 121. A tension spring 122 attached to the key release lever 117 and to a tab 123 serves to bias the key release lever 117 clockwise about its pivot post 119, the limit of such clockwise movement being determined by the stop 124 extending sidewardly from the plate 62. The lower portion of the key release lever extends sidewardly and is shaped so that its free end has an inclined margin 126.

The tip of the key release lever 117 extends between two spaced plates 127 which are pivotally supported at 125 on the key lever 76. Secured between the plates 127 is a trigger member 128. The member 128 is provided with a sidewardly extending portion 129 having an inclined surface 131. As may be seen in FIG. 11, the adjacent end of the key release lever is spaced somewhat below the extending portion 131. The trigger member is further provided with a sidewardly extending tab 132 to which is attached a tension spring 133, the other end of the spring 133 being anchored to the plate 62. The trigger member further includes sidewardly extending elements 134 and 136 which have a slight downward inclination, the free ends engaging the adjacent upper edge of the key lever 76 to limit the pivotal motion' of the plates 127 and the trigger member 128 carried thereby with relation to the key lever 76. From the foregoing it will be evident that the trigger member 128 is normally in the position shown in FIG. 11, this position being delined by engagement of the lower edge of the tab 134 with the upper edge of the key lever 76, the spring '133 serving to urge the trigger member into this position. It will be further understood that the trigger member is capable of limited pivotal motion with relation to the key lever 76, the magnitude of such motion being defined by engagement of the tab 136 with the upper edge of the key lever 76, such motion taking place against the force exerted by the spring 133. The key lever 76 is pivotally supported at 137 adjacent is right hand end, a half-loop wire spring 138 extending between the lever 76 and the flange 66 serves to urge the lever upwardly and functions as a return spring for the key lever 76.

Referring to FIGS. 11, 12 and 13, the operation of the just described key tripping mechanism will now be set out. With the parts in-their position of FIG. 11, although the shaft 42 is rotating uniformly counter-clockwise, the lever 86 remains in its quiescent position since the periphery of the shaft 42 clears the adjacent serrated margin of the cam 99. When the upwardly extending end of the key lever 76 is struckthe initial downward movement of the lever causes the engagement of the lower edge of the extending portion 129 of the trigger member 128 to engage the upper edge of the sidewardly extending portion of the key release lever 117. Further downward motion of the key lever 76 pivots the key release lever counter-clockwise about its pivot post 119. This motion causes the upper end of the key release lever 117 to move leftwardly unlatching the free end of the lever 86 whereupon the lever 86 is pivoted sharply counter-clockwise about its pivot 94 under the force exerted by the spring 104. This movement of the lever 86 lowers the cam into engagement with the rubber exterior of the shaft 42. It will be noted that when the cam 99 is thus dropped upon the shaft 42, the shaft engages a low area on the cam permitting the pin 102 to fall below the end of the stop finger 103 thereby freeing the cam for clockwise rotation as soon as it engages the shaft 42. As will be evident from FIG. 12, when the lever 86 is released by the trigger member 128, the key lever 76 has not reached the downward limit of its stroke and an appreciable cushioning overtravel of the key lever 76 is available. Release of the key lever 76 subsequent to its tripping of the trigger member 128 permits the lever 76 to return to its quiescent position of FIG. 11, the inclined upper edge 131 of the trigger member 128 engaging the inclined margin 126 at the free end of the key release lever 117 causing the trigger member 128 to pivot counter-clockwise slightly with relation to the lever 76 to permit the trigger member to ride up and over the adjacent free end of the release lever 117.

As soon as the cam 99 has engaged the shaft 42 the cam will be rotated clockwise by the shaft causing the lobe 141 of the cam to engage the shaft. This causes the lever 86 to move to its position of FIG. 13 wherein the right hand end of the lever 86 is moved downwardly, giving a downward impulse to the extending end 97 of the perforator device key lever. This downward motion of the extending portion 97 of the perforator key causes the perforator to transcribe the indicated signal on the tape. The perforator is thus actuated by the adjacent end of the lever 86 with the power for the actuation being supplied by the shaft 42 and its drive motor, the fo-rcerequired by the operator in striking the key lever 76 being merely that required to unlatch the actuating lever 86. It will be noted that the lobe 141 of the cam extends over a considerable portion of the cam periphery so that there is a downward dwell of appreciable duration by the right hand end lever 86 thereby preventing any undesired rebound of key 97 or of the mechanical linkage actuated thereby.

As the cam 99 is rotated further in clockwise direction the lever 86 is retained in its position of FIG. 13 with the stop finger 103 extending between the two spaced plates forming the cam 99. As the drop-off area 142 of the cam engages the shaft 42 the lever 86 is returned to its position of FIG. 11 with its extending end 92 again latching against the end 118 of the key release lever 117. As the cam 99 returns to its position of FIG. 11 it loses contact with the shaft 42, the clockwise motion of the cam being released by engagement of the stop finger 103 with the pin 2. The key tripping mechanism is thus reset for the next actuating cycle of the key lever 76.

The key levers of perforator structures are normally arranged so that only a single key can be down at any particular instant. If one key is held down and another key struck, the last struck key lever will not move down into actuated position. If two keys on the attachment of. the present invention are struck simultaneously, the two corresponding levers 86 will attempt to depress the corresponding perforator key portions '97 but will be held by the immovability of the perforator key portions 97. Under these conditions, rotation of the corresponding cams 99 would displace the levers 86 upwardly with relation to fulcrum points 94, the overload springs 107 absorbing the force applied to the levers 86. If one key of the attachment of the present invention is struck and striking of a second key closely follows, the first struck key will, through its corresponding lever 86, actuate the proper perforator key portion 97. Actuation of the second-struck key will result in dropping of "its corresponding cam 99 into contact with shaft 42 sufiiciently to clear the corresponding lstop finger 103. With one perforator key portion already down, in actuated position, the perforator key portion to be actuated by the secondstruck key will resist downward motion and the corresponding overload spring 107 will absorb the force transmitted by the cam. As the shaft 42 leaves the lobe 141 of the cam dropped by the first-struck key, the corresponding perforator key portion 97 will move upwardly permitting the perfiorator key portion 97 corresponding to the second-struck key to move downwardly through its normal cycle. The arrangement of the linkage between the keyboard of the attachment of the present invention and the perforator key portions is thus such that striking the attachment keys irregularly, that is, at irregular intervals, will not disturb the proper sequence of operation of the perforator.

Since the shaft 42 must be rotated to reset the trip mechanism, particularly cam 99 to its position of FIG. 11, it is advisable to provide a means for locking the actuating levers 86 during the period when the apparatus is not in use, that is, during the period when the motor 61 is deenergized. One such locking means is illustrated in FIGS. 16 and 17. This means may include a shaft 151 which spans the side plates 18 and 19 and is journaled in the apertures 152 (FIG. 2) in the side plates. In FIG. 16, the side plate 19, mounting the electrical solenoid 153, is omitted for purposes of clarity. As will be evident from FIG. 16 the solenoid includes a plunger 154 having a pivotal connection at 156 with a tab 157 rigidly supported on plate or bracket 158. The plate is rigidly secured to the shaft 151 by any suitable means such as screws 159. The plate 158 extends across the space between the side plates 18 and 19 and, when the solenoid 153 is in deenergized position as shown in FIG. 16, the lower edge of the plate 158 engages the adjacent ends of the actuating levers 86 preventing upward motion of the lever ends should the key levers 76 be depressed. With the locking means in its position of FIG. 16 actuation of the key levers 75 merely rocks the respective trigger members 128 without unlatching movement of the actuating levers 86. As will be evident from FIG. 17, wherein side plate 18 has been removed for purposes of clarity, a spring anchoring pin 161 extends from the plate 18 and supports one end of a tension spring 162. The tension spring 162 is secured to a bracket 163 rigidly mounted on the plate 158. The spring 162 biases the plate 158 to the locking position of FIGS. 16 and 17. When the solenoid 153 is energized, the plate 158 is raised to its broken line position of FIGS. 16 and 17 thereby releasing the actuating levers 86 for operation. It will be understood that the solenoid 153 might be energized by means of a switch separate from the control switch for the motor 61 or might be wired in parallel with the motor so that the solenoid and motor could be controlled by a single switch. It will be understood that the actuating means could take the form of a positioning motor other than the solenoid form identified at 153.

It will be evident from the foregoing that the present invention provides a power boosted keyboard attachment for conventional tape perforator devices which can be incorporated into the perforating device without constructional changes or alterations in the device other than the foreshortening of the keyboard device key levers. The arrangement of the tripping mechanism in the present invention is such that only a relatively short easy stroke, of the order of three-sixteenths of an inch is all that is required to trip the actuating levers. An overload means (spring 107) is provided for overcoming situations in which the actuating levers may be held against clockwise pivotal movement. As will be evident from FIG. 9, by properly dimensioning the key levers 76, the keys may be uniformly spaced from each other both horizontally and vertically. The mounting of each key trip mechanism on an individual plate 62 and the arrangement for supporting each of the plates 62 is an important feature of the present invention. As previously mentioned, the arrangement permits removal of each plate and the trip mechanism carried thereby mer-lly b3 removal of the top bar 27 and withdrawal of the shaft 42. The clutch or motion transmission means described with reference to FIG. 7 permits relatively large misalignment of the shaft 42 with the motor shaft 58 and also permits convenient operation of the coupling when the shaft 42 is removed from the assembly.

While the invention has been disclosed and described in some detail in the drawings and foregoing description, they are to be considered as illustrative and not restrictive in character, as other modifications may readily suggest themselves to persons skilled in this art and within the broad scope of the invention, reference being had to the appended claims.

What is claimed is:

1. A power boosted keyboard assembly comprising a frame which includes spaced end plates and spaced transversely slotted bars extending between said end plates, corresponding slots in said bars being aligned with each other, a plurality of key trip assemblies within said frame, said key trip assemblies each including a mounting plate having portions received in corresponding ones of said bar slots, a key lever pivotally supported on each of said mounting plates and having a portion extending into a position facilitating striking by the keyboard operator, an actuating lever pivotally supported intermediate its ends on each of said plates, said pivotal support for said actuating lever permitting displacement of said lever in a direction normal to its axis of pivotal movement, an overload spring supported on said plate adapted to engage said actuating lever adjacent its pivot axis upon substantial displacement of said lever and to resist further displacement thereof, a cam rotatably supported on said actu ating lever, a drive shaft extending between said end plates, each of said mounting plates having apertures therein accommodating said drive shaft, power means for rotating said drive shaft, each of said cams being retained out of engagement with said drive shaft when its actuating lever is in a first position and rotated by said drive shaft to provide a pivotal motion impulse to its actuating lever when its said actuating lever is in a second position, and latching means extending between each of said key levers and actuating levers, whereby when a key lever is struck by the keyboard operator its corresponding actuating lever is released to move from its said first position to its said second position.

2. A power boosted keyboard assembly comprising a frame, a plurality of key trip assemblies within said frame, each including a mounting plate, a key lever pivotally supported on each of said mounting plates and having a portion extending into a position facilitating striking by the keyboard operator, an actuating lever pivotally supported intermediate its ends on each of said plates, said pivotal support for said actuating lever permitting displacement of said lever in a direction normal to its axis of pivotal movement, an overload spring supported on said plate adapted to engage said actuating lever adjacent its pivot axis upon substantial displacement of said lever and to resist further displacement thereof, a cam rotatably supported on said actuating lever, a drive shaft extending through said frame, each of said mounting plates having apertures therein accommodating said drive shaft, power means for rotating said drive shaft, each of said cams being retained out of engagement with said drive shaft when its actuating lever is in a first position and rotated by said drive shaft to provide a pivotal motion impulse to its actuating lever when its said actuating lever is in a second position, and latching means extending between each of said key levers and actuating levers, whereby when a key lever is struck by the keyboard operator its corresponding actuating lever is released to move from its said first position to its said second position.

3. A power boosted keyboard assembly comprising a frame, a plurality of key trip assemblies within said frame, each including a mounting plate, a key lever pivotally supported on each of said mounting plates and having a portion extending into a position facilitating striking by the keyboard operator, an actuating lever pivotally supported on each of said plates, a cam rotatably supported on said actuating lever, a drive shaft extending through said frame, each of said mounting plates having apertures therein accommodating said drive shaft, power means for rotating said drive shaft, each of'said cams being retained out of engagement with said drive shaft when its actuating lever is in a first position and rotated by said drive shaft to provide a pivotal motion impulse to its actuating lever when its said actuating lever is in a second position, and latching means extending between each of said key levers and actuating levers, whereby when a key lever is struck by the keyboard operator its corresponding actuating lever is released to move from its said first position to its said second position.

4. A power boosted keyboard assembly comprising a frame, a plurality of key trip assemblies within said frame, each including a mounting plate, a key lever pivotally supported on each of said mounting plates and having a portion extending into a position facilitating striking by the keyboard operator, an actuating lever pivotally supported on each of said plates, a cam rotatably supported on said actuating lever, a drive shaft extending into said frame and adjacent said cams, power means for rotating said drive shaft, each of said cams being retained out of engagement with said drive shaft when its actuating lever is in a first position and rotated by said drive shaft to provide a pivotal motion impulse to its actuating lever when its said actuating lever is in a second position, and latching means extending between each of said key levers and actuating levers, whereby when a key lever is struck by the keyboard operator its corresponding actuating lever is released to move from its said first position to its said second position.

5. A power boosted keyboard assembly comprising a frame which includes spaced end plates and three spaced transversely slotted bars extending therebetween, corre sponding slots in said bars being aligned with each other, a plurality of mounting plates within said frame, each of said mounting plates carrying a key trip mechanism and having portions received Within corresponding ones of said bar slots, two of said portions on each mounting plate being spaced along one margin of the plate and the other portion being located on the opposite margin of each of the plates, a drive shaft supported at opposite ends by said end plates and removable therefrom, said drive shaft extending through registering apertures in said mounting plates, the bar receiving said other portions of said mounting plates being removable from said end plates, whereby with said last mentioned bar and said drive shaft removed from said frame said mounting plates may be removed individually from the frame for repair or replacement of the key trip mechanism carried thereby.

6. In a power boosted keyboard assembly, a frame which includes spaced end plates, key trip assembly mounting plates disposed in spaced relation between said end plates, a drive shaft supported at opposite ends by said end plates and removable therefrom, said drive shaft extending through registering apertures in said mounting plates and having a counterbore spanned by an internal pin at one end of the drive shaft, an electric drive motor mounted exteriorly of one of said end plates, and means for coupling said drive shaft to said motor comprising a coiled spring having flattened, hooked ends, one end of said spring being received in said counterbore and hooked over said pin, a hub having a bifurcated end mounted on the motor shaft, the other flattened end of said spring extending into the bifurcated end of said hub, whereby rotary motion is transmitted from said hub to said drive shaft through said spring with said spring ac- 11 commodating substantial misalignment of said drive shaft and hub.

7. In a power boosted keyboard assembly, a plurality of type-action mounting plates each having an aperture therethrough, a frame enclosing said plates, spaced stationary means in said frame gripping each of said plates and holding them in spaced parallel relation with their said apertures substantially in register, said frame including a plurality of members extending transversely across said plates, one of said members being removable from said frame to release said plates from said frame, a power drive shaft removably supported within said frame and extending through said registering apertures in said References Cited in the file of this patent UNITED STATES PATENTS 2,737,279 Schremp Mar. 6, 1956 2,897,941 Dodge Aug. 4, 1959 2,938,615 Donnan et a1. May 31, 1960 2,976,977 Israelson et a1. Mar. 28, 1961 

7. IN A POWER BOOSTED KEYBOARD ASSEMBLY, A PLURALITY OF TYPE-ACTION MOUNTING PLATES EACH HAVING AN APERTURE THERETHROUGH, A FRAME ENCLOSING SAID PLATES, SPACED STATIONARY MEANS IN SAID FRAME GRIPPING EACH OF SAID PLATES AND HOLDING THEM IN SPACED PARALLEL RELATION WITH THEIR SAID APERTURES SUBSTANTIALLY IN REGISTER, SAID FRAME INCLUDING A PLURALITY OF MEMBERS EXTENDING TRANSVERSELY ACROSS SAID PLATES, ONE OF SAID MEMBERS BEING REMOVABLE FROM SAID FRAME TO RELEASE SAID PLATES FROM SAID FRAME, A POWER DRIVE SHAFT REMOVABLY SUPPORTED WITHIN SAID FRAME AND EXTENDING THROUGH SAID REGISTERING APERTURES IN SAID PLATES, WHEREBY REMOVAL OF SAID REMOVABLE MEMBER AND SAID DRIVE SHAFT FROM SAID FRAME PERMITS SAID PLATES TO BE REMOVED INDIVIDUALLY FROM THE FRAME FOR REPAIR OR REPLACEMENT. 